feat(ai): Auto-Rotate & Face Alignment Correction (#2083)

[Dev1822]

Description

Implements pre-processing step that detects face tilt via eye landmarks and auto-rotates the image so the face is perfectly level before cropping. Closes #2083.

Changes

New: python-ai-service/app/services/face_align.py

• Detects face using OpenCV Haar cascade
• Detects eyes within the upper 60% of the face ROI
• Calculates roll angle via arctan2 between eye centers
• Falls back to PCA-based roll estimation on Canny edges when eyes aren't found
• Rotates the image by the negative of the detected angle (white border fill)
• Clamps correction to +/-25 degrees to avoid incorrect rotations on non-frontal photos

Modified: python-ai-service/app/routes/process_routes.py

• POST /remove-bg: Auto-rotation now runs as a pre-processing step before background removal (silent - if no face is detected, processing continues without rotation)
• New POST /auto-rotate: Standalone endpoint that accepts a multipart image and returns the corrected PNG with X-Roll-Degrees and X-Eyes-Detected response headers

Modified: python-ai-service/app/routes/compliance_routes.py

• POST /auto-correct: Added auto-rotate as a new issue type alongside the existing tilt type
• The existing tilt type now also uses the new face_align module (replacing the previous inline implementation)

New: python-ai-service/app/services/test_face_align.py

• 11 unit tests covering face detection, eye roll detection, auto-rotate edge cases, and data structures

Testing

All 11 tests pass.

API Usage

Standalone auto-rotate

curl -X POST http://localhost:8000/auto-rotate -F "image=@selfie.jpg"

Returns corrected PNG with metadata headers.

Part of processing pipeline

Auto-rotation is now applied automatically in POST /remove-bg before background removal - no additional parameters needed.

Via compliance auto-correct

POST /api/compliance/auto-correct
{ "file_path": "uploads/photo.jpg", "issue": "auto-rotate" }

[vercel]

@Dev1822 is attempting to deploy a commit to the souma9830's projects Team on Vercel.

A member of the Team first needs to authorize it.